Fuel feeding system



FUEL FEEDING SYSTEM 4 Sheets-Sheet 1 Filed March 50, 1938 mg; r 0M 3 2%HA6 4 Z vm o vw FW r ,f n

Dec. 19, 1939.

E. C. PHILLIPS ET AL FUEL FEEDING SYSTEM Filed March 30, 1938 544 541.Les-1.15 L ,4spEL/N R441 E. GRAEV lrroewe'y:

4 Sheets-Sheet 2 Dec. 19, 1939.

E. c. PHILLIPS ET AL 6 FUEL FEEDING SYSTEM Filed March 30, 1938 4Sheets-Sheet 3 LCTRIC MOTOR) 1939. E. c. PHILLIPS ET AL 2,133,586

FUEL FEEDING SYSTEM Filed March 30, 1938 4 Sheets-Sheet 4 laws/V700:EWELL 0. pH/LL/PS, LESLIE L AsPEL/AI,

R441 E. GEEK Patented Dec. 19, 1939 UNITED STATES PATENT OFFICE FUELFEEDING SYSTEM Ewell 0. Phillips and Leslie and Ralph E. Grey, Osborn,

Application March 30,

23 Claims.

(Granted under the a amended April 30,

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

This invention relates to a system for controlling power delivered froma source to a delivery point, and more particularly to an hydraulicsystem for controlling the transmission of power, and is adapted for usein connection with the supplying of liquid fuel or other fluid from asource of supply to a delivery point, and is especially useful inconnection with the supply of gasoline from a supply tank to an internalcombustion engine remote from said tank.

It has been found that where, in the case of aircraft, the fuel isstored in a tank remote from the engine, supply difficulties areencountered due to vapor locks formed in the conduits. Heretofore, thefuel has been drawn from the fuel tank and fed under pressure to theengine, by means of a reciprocating air or reciprocating compressionpump which is driven by a source of power and a fluid motor driven pumplocated at or adjacent to the source of fuel supply, the reciprocatingair or reciprocating compression pump serving to supply driving fluidunder pressure to the fluid motor driven pump, and the fluid motordriven pump serving to draw fuel from the source of fuel supply andforcing, under pressure, the fuel so drawn by the fluid motor drivenpump to the point of delivery, provision being made for controlling thepressure and amount of. the fluid supplied to the fluid motor drivenpump by the pressure or amount of liquid fuel delivered by the fluidmotor driven pump to the point of delivery, decreasing the pressure andamount of fluid supplied to the fluid motor driven pump with increaseabove normal in the pressure or amount of the fuel at the point ofdelivery, and increasing the pressure and amount of fluid supplied tothe fluid motor driven pump on decrease below normal in the pressure oramount of the fuel at the point of delivery.

A further conventional method of supplying fuel from a source of supplyto an engine at a given pressure is that of. employing a positivedisplacement fuel pump, driven directly by the engine, the fuel supplypressure being controlled by shunting the fuel pump by the use of apressure relief valve.

These known systems, however, have certain disadvantages. Areciprocating compression pump in the first mentioned system has thedisadvantage that it depends for its output upon the atmosphericpressure which varies with L. Aspelin, Dayton, Ohio 1938, Serial No.199,042

ct of March 3, 1883, as 1928; 370 0. G. 757) change in altitude so thata system of this character designed for high altitude operation, wherethe atmosphere is less dense or rarefied, would be extremely oversizefor low altitude operation.

The expansion of a compressible fluid as it 5 passes through the drivingmotor results in a lowering of its temperature and in the case of airwould cause a condensation and freezing of the moisture in the air. Insuch a system, therefore, satisfactory operation makes it imperativethat the air be Warm. This can only be accomplished by applying heatfrom an external source.

Sudden changes in the demand of. the fuel supply at the point ofdelivery require instantaneous response of the fuel supply pump so thatwhere the fluid motor driven pump is driven by a compressible fluidunder pressure that is built up in the system, the change in supply offuel to the point of delivery can not be instantaneous because of thecompressibility of the fluid and the consequent time lag in building upthe fluid pressure by the compression pump and delivering the same tothe fluid driven motor.

A system of this character in which reciprocating compressors, motors,or pumps are utilized in the fuel path have the further disadvantage ofproducing, by reason of the presence of valves, vapor lock which isbrought about by the fuel undergoing a drop in pressure as it passesthrough the valves and particularly so through the suction valve where apartial vacuum is created inside the pump on the suction stroke. At highaltitudes, where the pressure at the inlet of the valve is already nearthe boiling pressure of. the fuel, slight reductions in pressure inpumping the fuel through the valve will cause almost instantaneousvaporization of the more volatile fractions of the fuel and will resultin vapor lock condition, rendering such a system of no practical utilityin aircraft. 40

It is well known that the pressure of a fluid pressure system will havea tendency to hunt or oscillate if, in such a system, the pressure ofthe fluid supplied is controlled, as a function of the change inpressure of the fluid supplied. These. oscillations, in the absence ofprovision for dampening the same, regenerate within the system andbecome so great as to render the system ineffective when a substantiallyconstant pressure is desired.

In the second-mentioned system, the excess fuel being forced through therelief valve represents wasted work and horsepower. When the inlet ofthe fluid pump is subjected to pressures and temperatures near thepressure and. temper- 5 ature at which the fluid changes form (gaseousto liquid or vice versa) the drop in pressure encountered by the excessliquid when passing through the relief valve causes vapor to form, whichvapor when returned to the pump suction vapor locks the pump untilpumping ceases. To illustrate, this drop in pressure in a present-dayairplane fuel system operating at 40,000 feet altitude is fromapproximately 18 pounds per square inch absolute carburetor pressure toapproximately 2 pounds per square inch absolute atmospheric pressure.The relief valve controls the pressure at the point of discharge fromthe pump (provided it is mounted on the pump) and not at the point ofconsumption, therefore when the point of consumption is remote from thepump and this difference in elevation (static head) of the two changes(as in airplane maneuvering) the pressure at the point of consumptionchanges from the discharge pressure of the fluid pump in accordance withthis change in static head.

Our invention, therefore, has for one of its objects to provide aself-contained hydraulic transmission for supplying fuel from a sourceof supply to a point of delivery, the speed of the transmission beingmade variable as a function of the pressure of the fluid supplied at thepoint of delivery.

It is another object of our invention to provide, in a system of thischaracter, means for dampening the oscillations of the pressure in thesystem to a minimum. This is accomplished by retarding the rate ofchange of a pressure acting directly or indirectly on a speed controlelement which functions in response to the variations in the pressure ofthe fluid that is being supplied to the point of delivery.

It is a still further object of our invention to provide, in a system ofthis character, a speed control valve arrangement that is balanced bothagainst pressure and velocity of the transmission fluid.

It is a further object of our invention to provide a system of thischaracter in which pulsations are reduced to a minimum by the provisionof positive fluid displacement devices of the rotary type.

A further object of our invention is to provide, in a system of thischaracter, means for maintaining at all times a substantially constantdifferential between the carburetor air inlet pressure and the fuelpressure at the point of delivery regardless of pressure variations ofthe ambient atmosphere.

Other and further objects of our invention will appear from a moredetailed description of our invention.

In the drawings which form a part of the specification:

Figure 1 illustrates diagrammatically one embodiment of this inventionin which the speed of the hydraulic transmission is controlled byregulating the supply of motive liquid to the hydraulic generator.

Figure 2 is a sectional elevational view of the fuel pressure responsivevalve regulator for regulating the supply of motive liquid to thehydraulic generator, shown in Figure 1, showing a normal predeterminedoperating position in dotted outline;

Figure 3 is a sectional view taken on the line 33 of Figure 2.

Figure 4 is a sectional elevational view of the damping means shown inFigure 1 for damping out pressure oscillation of the pressure operatedspeed control valve.

Figure 5 is a sectional elevational view of the hydraulic generatorshown in Figure 1 for transmitting liquid under pressure to an hydraulicmotor of the hydraulic motor driven pump.

, Figure 6 is a sectional elevational View of the motor pump shown inFigure 1.

Figure 7 is a diagrammatic sectional elevational view of a furtherembodiment of this invention showing a unitary assembly of valveregulator and pressure variation dampener.

Figure 8 is a view similar to Figure 1, illustrating a still furtherembodiment of this invention in which the speed of the hydraulic motorof the fluid driven pump is controlled by regulating the supply of fluidto the hydraulic motor at the output side of the hydraulic generator,and showing further a variation for damping the pressure oscillations ofthe valve regulator.

Figure 9 is a further variation of a detail of this invention.

In the embodiment shown in Figure 1, which illustrates the means forcarrying out this invention, as applied to the supply of fuel from afuel tank H), which may be of manifold compartment type and convenientlylocated in any position on the airplane (not shown), to an internalcombustion engine l2, the fuel being delivered through a multi-way cockM, a strainer Hi, from which it is delivered to the carburetor I8,through fluid driven positive displacement pump 20 by means of anhydraulic transmission 22 or by means of a hand pump 24, the hand pumpbeing normally inoperative. The hand pump is provided with a pressurerelief valve (not shown), for relieving the fuel pressure when thepressure, due to excessive pumping either manually or to failure of thetransmission control, reaches a slightly higher predetermined pressurethan the pressure at which the system is set to operate.

The gear pump 20 and the hydraulic motor which is preferably of therotary vane type as described in Patent No. 2,083,560, dated June 5,1937, are arranged in a unitary assembly and are drivingly connectedtogether through a coupling 28 of well known construction. The motive oroperating liquid is supplied to the hydraulic motor by means of anhydraulic generator 30 which, as illustrated, is of the well known gearpump type similar to that shown in Figure 6 and, as illustrated in thisembodiment, is driven by the engine I2, communication between thehydraulic generator 30 and the hydraulic motor 26 being established by apipe 32 connecting the output side of the generator to the input side ofthe motor, the output side of the hydraulic motor being connected to theinput side of the generator through a pipe 34, a reserve supply andexpan sion chamber 36, and a fuel pressure responsive regulator 38 forcontrolling the supply of operating liquid to the input side of thegenerator.

The regulator, as shown in Figures 2 and 3, comprises a casing 40 and adifferentially controlled valve 42. The casing 40 consists of an uppersection 44, a lower section 46 and an intermediate section 48. Thisintermediate section has a motive fluid inlet connection 50 and anoutlet connection 52, and is formed with a projection 54 provided with apair of aligned openings formed with valve seats 56, 58 for seating twovalve discs 6%, 52 which are actuated by a metallic bellows 64 through avalve stem 66. The bellows 64 is confined within and constitutes withthe plate 68 a closure for the upper section 44 which is provided withan inlet ID for communicatively connecting through the conduit I2,Figure 1, the pressure chamber I4 and the fuel supply in the carburetorI8. The valve discs are also provided with a downwardly extending stemI6 that is seated in a recessed disc I8 that is yieldingly supported byan adjustable compression spring disposed within the lower section 46 ofthe housing, and mounted on a movable lower seat 82 that is providedwith cars 84 that are received in guiding relation with guide slots 86.An adjusting screw 88 is provided for varying the tension of the spring80. This screw is threadedly connected with the lower spring seat and isheld in fixed relation to the section by means of a flange 90 and locknut 92. The threaded portion of the adjusting screw terminatessufficiently short of the upper end of the screw to limit the tensionapplied to the spring. The spring, tensioned to a predetermined valuedetermines the normal operating position of the valve. The hydraulictransmission system is self-contained and is filled through an opening94, in the expansion chamber 36, with a liquid, preferably a light oilwhich serves as a lubricant for the different operating parts of thetransmission system, as well as a motive fluid.

The expansion chamber shown in Figure 4 is connected in the line 34 andis provided with inlet connection 96 and an outlet connection 98 forrespectively establishing communication with the output side of thehydraulic motor 26 and the inlet 56 of the motive fluid regulator. Theexpansion tank is divided into two chambers I00, I02 by a partition I04.Communication between the chambers is established through a relativelyrestricted orifice I06. The upper chamber is provided with an inlet I08which is communicatively connected with the air inlet III], Figure l, tothe carburetor so that the outlet side of the hydraulic transmissionsystem between the hydraulic motor and the motive fluid regulator willbe subject to approximately the same pressure as that to which thecarburetor air intake may be subject.

The level of the motive liquid in the expansion chamber is at all timesabove the partition and at a level such that sufficient expansion spaceis provided within the chamber to accommodate the surplus liquid whenthe demand by the generator from the expansion chamber is less than thesupply to the said chamber from the hydraulic motor. The level of theliquid in the chamber is measured by a sounding rod I I2 that isprovided with a reference mark II4 for indicating the desired level. Inorder to facilitate the passing of the rod into the chamber I02, thepartition is provided with a funnel shaped opening II6 which serves toguide the entering end of the rod through the partition.

The motive liquid is supplied to the positive displacement engine drivenhydraulic generator 30 from the expansion tank through the motor fluidregulator 38 and is in turn delivered under pressure to the hydraulicmotor 26 from which it is returned to the expansion tank 36. In theoperation of this system, communication is established between apreselected compartment of the fuel supply tank and the carburetorthrough the selector valve I4. Fuel is supplied to the carburetor andmaintained at a predetermined pressure as follows: The fuel pump being apositive displacement pump, its capacity will depend directly on thespeed of its rotation. Likewise, the hydraulic motor being also of thepositive displacement type, its speed is dependent upon the amount offluid supplied thereto. Since it is desired that a predeterminedpressure be maintained at the carburetor, it is obvious that, unless thespeed of the fuel pump is controlled in a direct relationship to therate of consumption of the fuel, the pressure in the carburetor willeither be excessively high or excessively low. In Order, therefore, tomaintain a substantially constant predetermined pressure in thecarburetor, the speed of th pump is varied as a function of the rate ofconsumption of the fuel and this is accomplished by controlling theamount of motive fluid supplied to the generator through the motivefluid regulator. When the consumption is the fuel delivery pressure willtend to decrease. This decrease in pressure, acting upon the bellowsallows the valve to be opened by the spring, thereby delivering anincreased quantity of motive fluid to the hydraulic generator which, inturn, increases the speed of the fuel pump, increasing the supply offuel thereby raising the fuel pressure at the point of delivery whichwill act upon the bellows so as to prevent further opening of the valveor movement of the same towards closed position depending upon thedifference in pressure between the bellows and the spring. t will beseen that, if the pressure increases in the carburetor, there will be acorresponding increase in pressure acting exteriorly on bellows whichwill tend to actuate the valve to restrict the flow of motive liquidthrough the valve, with the result that the speed of the hydraulic motoris therefore decreased and the supply of fuel to the carburetor islessened.

By utilizing a liquid hydraulic motive fluid, the delivery of the fuelby the fuel pump will be positive in its action and rapid in itsresponse to variations in the fuel pressure at the carburetor.

It will be seen that, as the motive fluid regulating val e is beingclosed and the valve opening restricted, the motive fluid generator,operating at a speed corresponding to the speed of the engine, willdisplace the fluid from the connecting line between the generator andthe valve at a rate greater than the supply of motive fluid from thetank through the valve during the closing thereof, with the result thatthere will be an increased supply of fluid from the fluid motor to thetank. This increased supply of fluid is utilized to build up a pressurein that part of the system between the exposed area of the regulatorvalve bellows and the hydraulic motor which opposes the movement of thediaphragm so that the rate of change in the orifice opening isdecreased. This built up pressure is brought about by causing the excessliquid to be forced through the restricted orifice in the partition ofthe ex pansion chamber. This built up pressure also has a retardinginfluence upon the speed of the fluid motor. Likewise, when the motivefluid regulator valve tends to open rapidly, the amount of motive fluidpumped by the generator is correspondingly increased and the pressure inthe system between the output of the hydraulic motor and the input ofthe generator is diminished by reason of the fact that the supply fromthe supply tank is restricted to the relatively small orifice in thepartition. This decrease in pressure has the effect of opposing therapid increase of oriflee opening. It will thus be seen that thepressure acting on one side of the bellows is increased when the valveis closing to oppose the increasing pressure within the bellows, andthat there will be a decrease in pressure on one side to oppose thediminishing pressure in the belon the outside.

lows when the bellows is opening and that these pressure variations arereduced by resistance to fluid flow to and from said tank.

Figure 7 shows a variation of the arrangement of the regulator andexpansion chamber described above in connection with Figure 1. In thisembodiment, the expansion chamber and the regulator constitute a unitarystructure II! which consists of a casing H8 that is divided into twocompartments I20, I22 by a partition I24. These two chambers arecommunicatively connected to each other through a relatively restrictedopening I26 through the partition I24. The compartment I22 iscommunicatively connected between the generator and the motor through adouble disc regulating valve I28 that is controlled by a bellows I30disposed within the compartment I 2!] which is vented through a pipe I32that communicates with the air inlet for the carburetor (as shown inFigure 1). The arrangement of the bellows and valve differs from thatshown in Figure 2 described above in that the beliows is arranged to beacted upon by the fluid pressure on the inside thereof instead of Thepartition is differentiated from that of Figure 4 in that it is providedwith a central opening to permit the passage of the valve stemtherethrough.

The operation of this system is similar to that shown in Figure 1, inthat the damping of the oscillations of the system is brought about bybuilding up a back pressure in that part of the system between theenclosed area of the bellows and the output side of the motor by reasonof the restriction of the flow of fluid through the restricted orificeI26 into the upper compartment I20 when the regulating valve is beingclosed, the exposed area in this embodiment being equal to thecross-sectional area of the valve stem. It will be obvious that, sincethe exposed area in this embodiment is less than the exposed area in theembodiment shown in Figure 1, all other conditions being the same, themagnitude of the damping effect will be less. This built up pres surehas the tendency of reducing the speed of the motor, with the resultthat the amount of fuel supplied to the carburetor is decreased, with aconsequent decrease in the controlling fuel pressure within the bellows.Damping of the oscillations of the system, when the controlling fuelpressure is less than the predetermined value as established by thepredeterminantly loaded spring, takes place by reason of the fact thatthe supply of motive fluid to the generator, not

'- shown, is less than the demand, as determined by the extent ofopening of the regulating valve, due to the restricted orifice openingwhich controls the supply of the motive fluid from the chamber to thevalve opening. Thus the motive fluid supply is gradually increased withthe result that the speed of the motor is gradually changed, which inturn produces a correspond ing gradual change in the controlling fuelpressure, thus reducing to a minimum the oscillations both in the motivefluid transmission system and in the fuel pressure supply system.

A further variation of our invention is shown in Figure 8. In thisembodiment, the control of the speed of the motor 26 is regulated bycontrolling the output side of the generator 30 as a function of thefuel pressure. The control of the operating fluid pressure isaccomplished by a regulator I34 that is disposed within a reserve supplychamber I36 which is communicatively connected between the input andoutput sides of the generator. The regulator is identical inconstruction as that shown in Figure '7 except that the double discs arearranged in reverse relation. This system is further distinguished fromthat shown in Figure 1 in that the generator is driven by a constantspeed electric motor. It will be seen that an increase in pressure inthe fuel supply will cause the valve discs to open, permitting a part ofthe motive fluid pressure to bypass to the input side of the generator,whereby the speed of the motor 25 is decreased and conversely, when thefluid pressure decreases the regulating valve I38 will be actuatedtowards the closed position as the pressure in the fuel supply decreasescausing a greater supply of motive fluid pressure to be transferred tothe motor 26 whereby the motor speed is increased and the supply of fuelpumped by pump 20 is correspondingly increased. In this system dampingof the oscillations thereof is accomplished by a restriction I40 in thefuel pressure line connecting the bellows and the carburetor. Therestriction serves to prolong the time of pressure transmission from thecarburetor to the bellows, decreasing the rate of movement of theregulating valve and consequently reduces oscillations of the system toa minimum.

Figure 9 shows a further variation of the expansion chamber shown inFigure 4 for use in connection with the system shown in Figure 1. Inthis embodiment, provision is made for the overflow of motive fluideither in the obverted or inverted position of the system. This type ofexpansion chamber is particularly useful in aircraft that may be subjectto inverted flight. For this purpose, the expansion chamber is providedwith a conical shaped partition I42 that serves to divide the expansionchamber into an upper chamber I44 and a lower chamber I46. The upper endof the cone is provided with an opening I48 to receive a sounding rodI511. The sounding rod has its inner end projecting through the openinginto the lower chamber and is provided with an axial hollow I52 and anorifice I54 for establishing communication between the upper and lowercompartments. The size of this restricted orifice determines the rate ofchange of pressure built up in the motive fluid system between theregulator (shown in Figure 2) and the output side of the motor 26, whichpressure acts in opposition to the movement of the bellows 64 (Figure 2)as described above. The size of this opening is preferably determined byexperiment and should be of such size as to give the most eiflcientpressure control. In order to facilitate the entering of the soundingrod into the opening I48, the upper end of the conical shaped partitionis provided with a conical shaped guiding portion I56. By providing aconical shaped partition, the upper chamber I44 extends below theorifice I54 so that the level I58 of the fluid in the expansion chamberwill be above the orifice either in the inverted or obverted position ofthe expansion chamber. Thus the system will be completely filled at alltimes and the motive fluid level will serve as a liquid seal against theentry of air into the motive fluid system and, at the same time, serveto dampen the oscillations of the system, as described in connectionwith Figure 1. In order to prevent the loss of the motive liquid fromthe expansion chamber in the inverted position thereof a vent tube I 60,communicatively connected with the upper chamber at $52, extendsdownwardly throughout substantially the length of the expansion chamber.

Obviously the same results as described in the various systems of ourinvention could be accomplished by an electrical system in which directcurrent is utilized as the motive energy and in which an electricgenerator serves in the same capacity as the hydraulic generator and anelectric motor, connected for driving the fuel pump, serves in the samecapacity as the hydraulic motor. An electric regulator such as avariable resistance serves in the same manner as the balanced valve ofthe hydraulic regulator to regulate the power supply to the motor ininverse proportion to the fuel pressure variations by use of a pressuredifferential means similar to that shown in the fluid systems above. Theresistance may be a rheostat of the wire wound type, or carbon blocks,or a carbon granule microphone, or a crystal. The electric regulatorwill be employed to control the speed of the motor by use of the shuntfield, or the series field, of either the electric motor or electricgenerator or possibly the resistance could be inserted directly in thearmature circuit.

The various embodiments of our invention are to be considered in allrespects as illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What we claim and desire to secure by United States Letters Patent is:

1. Means for maintaining the pressure of the fuel in the carburetorsubstantially constant at a predetermined value, said means comprising apower actuated pump means for supplying fuel to said carburetor, meansfor regulating the power supplied to said pump means including a powercontrol device and means responsive to changes in the pressure of saidfuel in said carburetor for controlling said device to maintain saidfuel pressure substantially constant at a predetermined value and meansfor damping said regulating means.

2. In combination with an internal combustion engine, a carburetortherefor, means for maintaining the pressure of the fuel in thecarburetor substantially constant at a predetermined pressure, saidmeans comprising fluid pressure actuated pump means for supplying fuelto said carburetor, means for regulating the supply of an operatingfluid pressure to said pump means including a fluid pressure controlvalve means responsive to changes in the pressure of said fuel in saidcarburetor for controlling said valve to maintain said fuel pressuresubstantially constant at a predetermined value, and means cooperatingwith said regulating means for damping abrupt changes in the control ofsaid valve with abrupt change in the demand of fuel by said engine.

3. In combination with an internal combustion engine, a carburetortherefor, an air intake for said carburetor, means for maintaining thepressure of the fuel in the carburetor substantially constant at apredetermined value in excess of air intake pressure, said meanscomprising fluid actuated pump means for supplying fuel to saidcarburetor, means for controlling the supply of an operating fluidpressure to said pump means, means responsive to changes in the pressureof said fuel in said carburetor for regulating said controlling means,and means operating to balance the effects of said air intake pressureon said pressure responsive means regardless of difference in the airintake pressure and the ambient atmospheric pressure.

4. In combination, fluid pressure actuated pump means for supplying afluid under pressure to a point of delivery, means for regulating thesupply of an operating fluid pressure to said pump means, meansresponsive to changes in the pressure of said first mentioned supply atthe point of delivery for controlling said regulating means, and meansfor damping the movements of said regulating control to prevent rapidchange in the regulation thereof.

5. In combination, fluid pressure actuated pump means for supplying afluid under pressure to a point of delivery, means for regulating thesupply of an operating fluid pressure to said pump means, meansresponsive to changes in the pressure of said first mentioned supply atthe point of delivery for controlling said regulating means and means toincrease the time duration of the application of the fuel pressure onsaid pressure responsive means during any change in the fluid supplypressure to thereby damp the operation of said regulating means.

6. In combination, a pressure generator, an hydraulically driven motorpump for delivering fluid under pressure, a regulator for controllingthe supply of an operating hydraulic pressure to said motor, means forestablishing a predetermined operating position for said regulator,means for changing the operating position of said regulator inaccordance with the differential pressure of said fluid pressure andsaid predetermined pressure, and means to prevent hunting of saidregulator.

7. In combination, a self-contained hydraulic transmission systemincluding a liquid pressure generator and a liquid pressure drivenmotorpump for establishing another fluid pressure, a predeterminatelyloaded liquid flow control means and means for regulating the speed ofsaid motor-pump as a function of the difference in the pressure of saidother pressure and the pressure of said predetermined load.

8. In combination, a self-contained hydraulic transmission systemincluding a liquid pressure generator and a liquid pressure drivenmotorpump for establishing another fluid pressure, an adjustablepredeterminately loaded liquid flow control means, means for regulatingthe speed of said motor-pump as a function of the difference in thepressure of said other fluid pressure and said loaded pressure, andmeans to prevent hunting of said regulating means.

9. Means for maintaining a substantially constant difference between thepressure of the fuel supply at a point of delivery and the inlet airpressure of the carburetor of an internal combustion engine comprising,in combination a fuel pump, a closed hydraulic transmission circuitincluding an hydraulic pressure generator, a motor drivingly connectedto said pump and driven by an operating liquid pressure generated bysaid generator, means actuated by and responsive to variations in saidfuel pressure for changing the speed of said fuel pump and means forbalancing said last mentioned means against the effects of said inletpressure regardless of change in pressure between the inlet pressure andthe ambient atmospheric pressure.

10. Means for controlling the pressure of the fuel supply at a point ofdelivery to an internal combustion engine by changing the speed of afuel pump comprising, in combination, an hydraulic generator, a motordrivingly connected to said pump and driven by an operating liquidpressure generated by said generator, means actuated by and responsiveto a variation in said fuel supply pressure for changing the speed ofsaid fuel pump, and means to increase the time duration of theapplication of the fuel pressure on said pressure responsive meansduring any change of fuel supply pressure to thereby damp theoscillations of said pressure responsive means.

11. Means for controlling the pressure of the fuel supply at a point ofdelivery to an internal combustion engine by changing the speed of afuel pump comprising, in combination, an hydraulic transmission systemincluding an hydraulic generator driven by said engine, a motordrivingly connected to said pump and driven by an operating liquidpressure generated by said generator, means between the output of saidmotor and input of said generator actuated by and responsive tovariations in said supply pressure from a predetermined value forcontrolling the liquid flow to said generator, a tank, an orificecommunicatively connecting said tank with the output of said motor inparallel with said last mentioned means, said restricted orificecontrolling the flow of fluid to an from said tank in a manner to reducethe amplitude of oscillations in said power transmission system withchange in the liquid flow control condition, by opposing the movementthereof substantially as a function of the rate of change in thepressure of said fuel supply to thereby reduce the amplitude ofoscillations in said power transmission system.

12. In a fluid transmission system a fluid pressure generator, a fluidpressure actuated device, a regulating valve for controlling the supplyof fluid pressure for operating said device, said regulating valve beingactuatable by and responsive to variations in the speed eifects of saiddevice for changing the speed of said device, and means for producing anincreasing opposition to the movement of said valve in proportion to thevariation in the fluid control.

13. In an hydraulic transmission system, a liquid pressure generator, aliquid pressure actuated device, a regulating valve for controlling thesupply of liquid pressure for operating said device, said regulatingvalve being actuatable by and responsive to variations in the speedeffects of said device for bypassing liquid pressure from the outputside of said generator to the input side thereof and means for dampingoscillations of said regulating valve with variations in the speedeffects.

14. Means for maintaining a substantially constant pressure differencebetween the fuel pressure and the inlet air pressure of the carburetorof an internal combustion engine, comprising, a power actuated pumpmeans for supplying fuel under pressure to said carburetor, and meansfor regulating the power supplied to said pump means including a powercontrol device and a predeterminately loaded pressure differentialresponsive means between the inlet air pressure and the fuel supplypressure for regulating said device in such a manner as to obtain apressure difference between the fuel pressure and the inlet air pressuresubstantially corresponding to said predetermined loading.

15. Means for maintaining a substantially constant pressure differencebetween the fuel pressure and the inlet air pressure of the carburetorof an internal combustion engine comprising, a fluid pressure actuatedpump means for supplying fuel under pressure to said carburetor, andmeans for regulating the supply of an operating fluid pressure to saidpump means including a valve and a predeterminately loaded pressuredifferential responsive means between the inlet air pressure and thefuel pressure for regulating said valve in such a manner as to obtain apressure difference between the fuel pressure and the inlet air pressuresubstantially corresponding to said predetermined loading.

16. Means for maintaining a substantially constant pressure differencebetween the fuel pressure and the inlet air pressure of the carburetorof an internal combustion engine comprising, a fluid pressure actuatedpump means for supplying fuel under pressure to said carburetor, andmeans for regulating the supply of an operating fluid pressure to saidpump means including a casing, a predeterminately loaded pressuresensitive means providing with said casing two separate pressurechambers, one of said chambers being communicatively connected with saidair inlet pressure and the other with said fuel pressure and a controldevice operated by said sensitive means in such a manner as to obtain apressure difference between the fuel pressure and air pressuresubstantially corresponding to said predetermined loading.

17. Means for maintaining a substantially constant pressure differencebetween the fuel pressure and the inlet air pressure of the carburetorof an internal combustion engine comprising, a fluid pressure actuatedpump means for supplying fuel under pressure to said carburetor, andmeans for regulating the supply of an operating fluid pressure to saidpump means including a casing, an adjustable predeterminately loadedpressure sensitive means providing with said casing two separatepressure chambers, one of said chambers being communicatively connectedwith said air inlet pressure and the other with said fuel pressure and acontrol device operated by said sensitive means in such a manner as toobtain a pressure difference between the fuel pressure and air pressuresubstantially corresponding to said predetermined loading.

18. In combination, a fluid pressure actuated motor pump for supplying afluid under pressure to a point of delivery, means for generating anoperating fluid pressure for said motor pump, a fluid flow control inseries circuit with and between the input side of said generator and theoutput side of said motor, pressure sensitive means in said circuit andresponsive to said means to produce pressure variations in the circuitbetween the output of said motor and the input of said generator inopposition to the fluid pressure variations acting on said flow controland caused by change in fluid pressure at the point of delivery and tosuch an extent as to prevent hunting of said flow control but to enableregulating movement thereof.

19. In combination, a fluid pressure actuated motor pump for supplying afluid under pressure to a point of delivery, means for generating anoperating fluid pressure for said motor pump, a fluid flow control inseries circuit with and between the input side of said generator and theoutput side of said motor, pressure sensitive means in said circuit andresponsive to said supply pressure for actuating said flow control, andmeans in said circuit between said flow control and the output of saidmotor to produce pressure variations that act on said pressure sensitivemeans in opposition to the pressure variations caused by change in fluidpressure at the point of delivery and to such an extent as to preventhunting of said flow control but to enable movement thereof.

20. In combination, a fluid pressure actuated motor pump for supplying afluid under pressure to a point of delivery, means for generating anoperating fluid pressure for said motor pump, a fluid flow control inseries circuit with and between the input side of said generator and theoutput side of said motor, pressure sensitive means in said circuit andresponsive to said supply pressure for actuating said flow control, andresistance means in said circuit between said flow control and theoutput of said motor to produce pressure variations that act on saidpressure sensitive means in opposition to the pressure variations causedby change in fluid pressure at the point of delivery and to such anextent as to prevent hunting of said flow control but to enable movementthereof.

21. Means for maintaining a substantially constant pressure differencebetween the fuel pressure and the inlet air pressure of an internalcombustion engine, comprising, a fluid pressure actuated motor pump forsupplying fuel under pressure to said carburetor, means for generatingan operating fluid pressure, fluid flow control means in series circuitwith and between the output side of said motor and the input side ofsaid generator, a predeterminately loaded pressure differentialresponsive means between the inlet air pressure and the fuel supplypressure for regulating said fluid flow control in such a manner as toobtain a pressure difierence between the fuel pressure and the inlet airpressure substantially corresponding to said predetermined loading, andmeans to produce the pressure variations that act on said pressuresensitive means in opposition to the pressure variations caused bychange in fluid pressure at the point of delivery and to such an extentas to prevent hunting of said flow control but to enable movementthereof.

22. Means for controlling the pressure of a fluid supply at a point ofdelivery by changing the speed of a fluid pump comprising, incombination, a fluid supply pump, a closed hydraulic transmissioncircuit including an hydraulic generator, a motor drivingly connected tosaid pump and driven by an operating liquid pressure generated by saidgenerator, means actuated by and responsive to variations in said supplyfor changing the speed of said pump and a tank having a restrictedcommunication with said circuit to retard the flow of liquid from saidtank to said circuit and vice versa and thereby produce forces acting toreduce the speed of operation of said pressure responsive means.

23. In combination, a fluid pressure actuated motor pump for supplying afluid under pressure to a point of delivery, means for generating anoperating liquid pressure for said motor pump, a liquid flow control inseries circuit with and between the input side of said generator and theoutput side of said motor, pressure sensitive means in said circuit andresponsive to said supply pressure for actuating said flow control, anda tank having a restricted communication with said circuit at a pointbetween said pressure sensitive means and the output of said motor toretard the liquid displacement efiect of said fluid flow control andsaid generating means from said circuit to said tank and vice versa,thereby producing forces tending to reduce the speed of operation ofsaid flow control with change in fluid supply pressure.

EWELL C. PHILLIPS. RALPH E. GREY. LESLIE L. ASPELIN.

